The present invention relates to a structure for supporting an automobile horn and, more particularly, an improved structure for supporting a horn on a motor vehicle having a radiator grille made of a synthetic resin.
The automobile horns are usually attached to a stationary part in the engine room of the automobiles. There are, however, many parts such as radiator for cooling the cooling water of the engine, condenser of the air conditioner and so forth which have to be mounted at the frontmost part of the engine room near the front grille, so that the designers are obliged to mount the horn at a portion of the engine room spaced from the front end of the latter. In consequence, the warning phone radiated from the horn is interrupted by the parts installed at the front part of the engine room, inevitably resulting in an attenuation or reduction of the level of sound pressure to shorten the reach of the warning phone. In fact, the reduction of the sound pressure level due to the presence of parts at the front part of the engine room well reaches 10 dB or more, so that is necessary to mount an automobile horn having a high output in order to compensate for the reduction of the sound pressure level.
The safety Standard of Japanese Road Transportation Vehicles states to effect that the sound level of the warning phone must fall within the region of between 90 dB and 115 dB as measured at a point 2 m ahead of the automobile. Thus, the automobile horn is required to have an output large enough to produce a sound pressure of at least 90 dB at the point 2 m ahead of the automobile. This means that, taking into account the 10 dB drop of sound pressure as stated before, the horn mounted in the engine room of the automobile must have an output large enough to provide a sound level of 100 dB at the point 2 m ahead of the automobile, assuming that no obstructing part is attached to the front end of the engine room. Considering the margin of the sound level, it is preferred that the horn has an output sufficiently large to provide a sound level of 105 dB or so at that point.
Thus, the automobile horn mounted in the engine room is required to have an unnecessarily high output, which in turn demands a horn of large volume and weight and consuming large electric power. This poses a problem, particularly, in small-sized automobiles having only limited space of engine room, because it is extremely difficult to preserve a suitable space for accommodating the horn.
To overcome these problems, it has been proposed to attach the horn to the rear side of the front bumper of the automobile. This solution, however, is found unacceptable because of unfavourable result caused by an invasion by rain water.
The attaching of the automobile horn to the stationary part in the automobile is made through the medium of a suitable stay member. This arrangement poses another problem of electrolytic corrosion of the terminal portion, because the body of the automobile horn is made of a metallic material. Since the stationary part connected to the chassis of the automobile usually constitutes the earthing side of the electric system, the automobile horn body is also at the grounding potential. Two terminals are exposed at the terminal portion of the horn, one of which is connected to the power source while the other is grounded through a horn switch. This means that a certain voltage or potential is always applied to the terminals of the terminal portion of the automobile horn, i.e. a certain potential difference between the terminal portion and the body of the automobile horn. Therefore, an electrolytic corrosion takes place when water comes between the body of the automobile horn and the terminal portion of the same, to cause a corrosion at the terminal portion. The problem of corrosion of terminal portion of the automobile horn and, hence, the dropping of the terminals, is serious particularly in the district having much snow fall, because in such district anti-freezing agent is sprayed on the road surface. In order to obviate this problem, various measures are taken such as the use of a water-proof connector, a relay for usually maintaining the terminal portion at the gounding potential and so forth. These measures, however, uneconomically raise the cost of the automobile.